Flumazenil potentiation of postoperative morphine analgesia

Objective: The goal of this study was to test the effect of concomitant adm inistration of flumazenil (FL) and morphine (MO) on immediate postoperative analgesia and the MO requirement to control pain in human beings. Design and Interventions: Thirty-six patients undergoing inguinal herniopla sty under lidocaine epidural anesthesia were enrolled in this double-blind, randomized, controlled study. On the first complaint of pain, either MO (2 mg) only or MO (2 mg) plus FL (0.2 mg) was administered. Additional doses of the same medications administered via a patient-controlled analgesia dev ice with a 10-minute lockout period were available thereafter. The study co ntinued for 2 hours after the loading doses of the medications were adminis tered, with an additional 2-hour period of observation. Results: Thirty-two patients completed the study. Both groups reached a sim ilar satisfactory equianalgesic state (2 in a 0-10 visual analogue scale). The MO plus FL group consumed 9.5 +/- 1.1 mg of MO versus 14.1 +/- 1.1 mg o f MO (p <0.001) in the MO only group. The MO plus FL patients were subjecti vely (visual analogue scale) more comfortable and less sedated than the MO patients. "Fine" coordination (using an electronic maze) and "coarse" coord ination (measured by transferring a pen from one hand to another as rapidly as possible with both arms placed inside an 80-cm metal frame) in the MO g roup were worse than in the MO plus FL group. End-tidal co(2) increased and blood pressure decreased in the MO group. There were few and insignificant side effects in the MO group. None of these patients required an MO antago nist, and recovery was prolonged in none. Conclusions: flumazenil afforded lower MO consumption during the immediate postoperative period. Cognitive, hemodynamic, and respiratory functions wer e better after MO plus FL than after MO alone.